Grinding machine



m m mm 5 G m Am, Hm G May 26, 1942.

Fiied March 27, 1940 14 Sheets-Sheet l mm i EREER T y 194 2., H. A.SILVEN GRINDING' MACHINE Filed March 27, 1940 14 Sheets-Sheet 2 grwambo'b ES HERBERT A.

SI VEN H. A. sin/EN 2,284,673

GRINDING MACHINE Filed March 27, 1940 14 Sheets-Sheet 3 10.2 [03 00 1/I74 I] l TRUING E XHA U5T PuRT HERBERT A. SILVE'N v ,P WW

May 26, 11942. H. A. SILVEN GRINDING MACHINE Filed March 27, 1940 l4Sheets-Sh'e'et 4 6762 HERBERT A. SILVEN y 1942- H. A. SILVEN 2,284,073

enmbme momma Fil ed March 27, 1940 14 Shee ts-Sheet 5 H m 77 1 0,10 5 v70 21 m ,lea

HERBER T A. SILVEN May 26, 1942. H. A. $ILVEN GRINDING MACHINE FiledMarch 27, 1940 l4 Sheets-Sheet m I8B HERBERT A. SILVEN /0 93N6 5 2 3 2 MQ. I 2 $3 2 2 J L m %w a my .2 2 3;? 46 7 97 7 a 86 6 $2 070. 22 wxww wwz 22333333 2 /w W 4 y 942. H. A. SILVEN GRINDING MACHINE 14 Sheets-Sheet7 Filed March 27, 1940 HERBERT A. S/LvEN y 6, 1942. v H A. siLvEN2,284,073

GRINDING momma FiJ ed March 27,1940 l4 Sheets-Sheet 8" gwm / I HERBERTA. SILVEN ay 2%, 1942. H. A. SHLVEN 2,2,073

GRINDING MACHINE Filed March 2'7, 1940 v 1.4 Sheets-Sheet 9 Z6] & f IE.2.3

HERBERT A. SILVEN 26, N42. HA. SILVEN 2,2973

GRINDING MACHINE Filed March 27, 1940- 14 Sheets-Sheet'lO May 26, l Q ASILVEN 2284,73

GRINDING MACHINE Filed March 27,, 194a 14 Sheets-Sheet 11 ay 26, 1942cH. A. SILVEN 4,

' GRINDING MACHINE Filed March 27', 1940 14 Sheets-Sheet l2 i ULLV'STRUKE y 1942- H. A. SILVEN 2,284,073

GRINDING MACHINE Filed March 27, 1940 t 14 Sheets-Sheet 14 SPEED RANGEF35 GRINDING" GRINDING.

HA ND Ila? W/ zzz Patented May 26, 192

UHTE STAT ES PATENT orrl cs- GRINDING MACHINE Herbert A. Silven,Worcester, Mass... assignor to Norton Company. Worcester, Mass, atcorporation of Massachusetts Application March 27, 1940, Serial no.326,224

19 Claims.

- ally and designed to operate according to the obiects heretoforegiven. Other objects will be in operation is finished. Another object ofthe invention is to provide a surface grinder in which the wheel and thework are relatively traversed, cross-fed at one or both ends ofthereciprocatory traverse, and fed relatively in a vertical positionafter'the entire surface has been covered.

Another object of the invention is to provide a surface grinder. of thetype iust indicated with automatic instrumentalities to reposition thegrinding wheel and work piece relatively in a vertical direction at theend of a grinding operation. Another object of the invention is tomeasure a grinding operation by the total number of complete passes overthe'work piece bringing the grinding operation to a'close at the end ofa predetermined number -of'such 'passes. Another obiect of the inventionis to provide a counting mechanism for a grinder with a complex seriesof 1' movements to determine a grinding operation at the end of apredetermined number of such move- Another object of the invention is toprovide a surface grinding machine with a reciprocatory table for thework piece, a column, a vertical slide and a horizontal wheel slide forthe grinding wheel, and hydraulic actuating mechanism for the table andslides with provision for man.-

ual feed or positioning of the table or any of the slides. Anotherobject of the invention is to provide hydraulic means to return thevertical slide to initial position after a grinding operation in orderto have. the machine ready for the next part obvious or in part pointedout hereinafter.

The invention accordinglyconsists in the features ofconstructiomcombinations of elements.

and arrangements of parts, as will be exemplified in the structure to behereinafter described, and

the scope of the application of which will be indicated in the followingclaims.

In the accompanying drawings in which is illustrated one of manypossible embodiments of the mechanical features of this invention,

Fig. 1 is a front elevation of a surface grinding machine embodying theinvention, showing much of the controlling apparatus that is within thebase or behind an apron in dotted lines:

' ating and controlling motors, cylinders and soleill noids to show thecomplete cycle of operation and the machine control;

Fig. 4 is a fragmentary front elevation, on an enlarged scale, of thebaseand table of the machine. illustrating part of the reciprocatorytraverse control and also the hand wheel feed for the table;

Fig. 5 is a cross-sectional view of the manually I operable tabletraversing mechanism taken approximately on the line 5 -5 of Fig. 4;v

Fig. 6 is a front elevation, on an enlarged scale,

of a table stop dog;

Fig. '7 is a vertical sectional view. taken approximately on the line1-1 of Fig. 8, showing the interlock between the manual and the 117-"draulic table traverse mechanisms;

Fig. 8 is a fragmentary plan view of the tabl reversing mechanism,showing the stop and start valve in section and also the manualtraversing mechanism;

Fig. 9 is a vertical sectional view taken approximately on the line 9-4of Figs. 8 and 4;

grinding operation. Another object of the intuating mechanism which issusceptible of quick and accurate control automatically and manu- F18.l0 is'a' vertical sectional view, on an enwhich is actuated by a tabledog and its connection to a vertical rod which controls the countingmechanism, and also illustrating a control for the speed of the table;

I Fig. 12 is a fragmentary sectional view, taken vertical direction;

Fig. 14 is a fragmentary front elevation, on an enlarged scale, takenapproximately on'the line 31 -31 of Fig. 33;

Fig. 38 is a dot and dash end view of the selector valve, showing thediflerent. positions of the valve stem, that is grinding, hand andtruing, and connecting body of the wheel slide reverse valve:

Fig. 39 is a fragmentary view, on an enlarged scale, takenapproximatelyon the line 33-33 of Fig. 30; and v Fig. 40 is a fragmentary plan view,on an en- 7 larged scale, of the sleeve in the selector valve,

enlarged scale, of the vertical wheel feedin mechanism and the controlstherefor;

Fig. 15 is a fragmentary sectional view, on em the line enlarg fl scale,taken i tratedin 'thefdrawings comprising a base 40 ll---l5ofFig.14;

Fig. 16 is a fragmentary sectional view taken approximately on the linelS-li of Fig. 15;

Fig. 17 is a fragmentary sectional view, on an enlarged scale, takenapproximately on the line l'l-ll of Fig.15;

Fig. 18 is a vertical sectional view taken approximately on the linel3-l8 oi Fig. 13;

Figs. 1,9, 20, 21 and .are all elevations of the vertical feedingmechanism, showing certain parts in section and also illustratingdifferent positions of the same parts so thatthe' cycle ofoperation maybe more readily understood;

Fig. 23 is a fragmentary sectional view, on an enlarged scale takenapproximately on the line 23-23 of Fig. 18;

Fig. 24 is aview similar. to that shown in Figs. 19 to 22 inclusive,showing Fig. 26 is a fragmentary vertical section taken approximately onthe line 2623 ofFlg. 14:

Fig. 27. is a fragmentary vertical sectional view,

certain parts in different positions; a

Jasa support for a transversely movable wheel on an enlargedscale, takenapproximately on the line 21-21. of Fig. 2 through the cross slide andFig. 29 is a fragmentary sectional view, on an enlarged scale. takenapproximately on the line 29-29 of Fig. 27;

Fig. 30 is a fragmentary vertical sectional view,

mechanism: 1 v

' on an enlarged scale, taken approximately on the i I line 30-40 ofFig. 1, showing the cross feeding- Fig. 31 is e fragmentaryhorizontalsectional.

approximately onv the line tl-ll of showing one of the V-ports forcontrolling the speed of the transverse indexing movement of thegrinding-wheel.

A surfacegrinding machine has been illuswhich supports 'a-longitudinallyreciprocable work supporting table 4i on theusual v-way 42 and the slide43 may be moved in a vertical direction.

The vertically movable slide 43 is provided with a horizontallyextending slideway which serves may comprise anti-friction rollers 5iand I2 (Figs.

2 and 27) whichare arranged at opposite ends of the wheel slide it andare supported thereon 5 by means of the shafts l3 and 64, respectively.

The rollers II and I2 ride upon the slideway 43 and serve as ananti-friction support'for the slide 50. A plate II which is bolted tothewheel slide 80 by means of screws 53 (Fig. 27) serves to guide the wheelslide Ill and to hold it in position upon the slideway 4!.

r The lower'portion of the vertical slide is vide an anti-frictionsupport, the wheel slide is provided with anti-friction rollers 53 and83 (Figs. 2, 27and 29lfwhichare supported oh shafts II andfl'iournalle'd in the wheel slide. A plate 02 which isboltedto the wheelslide "by screws It serves to prevent a lifting of the.wheel slide andalso serves 'as an additional means for guiding the wheel slide duringits transverse movemen In order to facilitate adjustment of the lowersliding elements. the rollers It and II are preferably supported by ananti-friction bearing and are formed integral with the studs II and IIbut eccentric relative-thereto. By a rotary adjustment of the studs 30and ii, the anti-friction rollers 58 and Il may be adjusted as desiredto take up any lost motion in the lower sliding part. A 'pair of locknuts are provided for the studs I3, 34. M and I which serve to clampapproximately on the line 3434. of Fig. 33;

Fig; 35 is a fragmentary sectional view taken approximately on the line35-45 of Fig. 33. showing a section through the transverse .feed wheel;

Fig. 36 is a fragmentary sectional view, on an enlarged scale, takenapproximately on the line 36,- of Fig. 34;

Fig. 37 is a fragmentary sectional view, on e1 to them in adjustedpomtions. outwardly extending end portions of the studs I3, 54. II andll are formed of a square cross-sectional shape whereby the studs may bereadily rotated by means of a wrench and when adjusted into the desiredposition maybe locked by tightening the lock nuts.

The cross slide or wheel slide ll serves as a support for a rotatablegrinding wheel I which is supported at one end of a rotatable wheelspindle II. The wheel spindle Cl is journalled in suitable bearings 51which are mounted in fixed relation with the wheel slide 50. Thebearings 81 are provided with the usual adjusting devices whereby thebearing may be adjusted to compensate for wear of the parts. 5

The grinding wheel spindle 58 may be driven by means of an electricmotor 58 which is adjustably supported on a bracket depending from thewheel slide 50 (Fig. 2). The motor ,58 is provided with a multipleV-groovepulley-88 which is connected by means of a multiple V-belt I0with a multiple V-groove pulley II which is mounted on the end of thewheel spindle 06.

The motor 68 is supported on a vertically ad- '15 justable plate I2(Figs. 2 and 27) which is adjustably supported on a depending slideway13 Y formed integral with the wheel slide 50. An

adjusting screw I4 is rotatably supported in a bracket 15 which isfixedly mounted on the depending portion of the wheel slide 50. The

- screw 14 is held against endwise movement in the bracket 15 but isarranged for a rotary movement relative thereto. The screw I4 is screwthreaded into a portion I8 of the suping belt III.

Hand table traverse If desired, the work supporting table lI may betraversed longitudinally by meansof a manually operable traversingmechanism (Figs. 4, 5

and 8) comprising a rack bar 80 which is fixedly mounted on the underside of the table I. A gear BI is mounted on the inner end of a rotat-.able shaft 82 whichflis journalled. in suitable anti-friction bearings83 and 84. The bearings 83 and 84 are supported within a slidablymounted sleeve 85 which is slidably keyed by fmeans of a key 85 withinan aperture 8'! which is 8 formed integral with an apron 88 fixedlymounted on the front of the machine base 50. A gear 5 89 is keyed on theleft-hand end of the shaft 82 (Fig. 5). The gear 89 meshes with a gearwhich is rotatably supported on a stud 9i. The stud 9| is fixedlymounted relative to the apron 88. A manually operable traverse wheel 92is supported to rotate with the gear 90.

The sleeve 85 is arranged for an axial sliding movement so that the gear8| may be readily moved into or out of mesh with the rack bar 80.

As illustrated in Figs. 5, 8 and 9, the gear 8i is shown as out of meshwith the rack bar and is held in this position by means of aspringpressed detent 93 (Fig. 8) which engages a V-notch 94 cut in theperiphery of the sleeve 85. When it is desired to traverse the table ll0 manually, the sleeve is moved toward the right (Fig. 5) toshift thegear 8i from the full line position (Figs. 5 and 8) into the dotted lineposition 8Ia in mesh with the rack bar 80, in

which position a second v-notch 95 is moved or,

into engagement with the detent 93 to hold the sleeve 85 in an operativeposition.

During the normal grinding operation the table 4| is preferablytraversed or reciprocated longitudinally by a hydraulically operatedr'nech- 70 anism to be hereinafter described and the hand traversemechanism is maintained in an inoperative position, such as that shownin Fig. 5, with the gear 8| out of mesh with the. rack bar 80. Themanual traverse mechanism, as 75 (Figs. 1, 3 and 5).

above described, is preferably interlocked with the hydraulic tabletraverse mechanism so that manual table traverse mechanism is locked inan inoperative position during the power traverse of the table.

Hydraulic table traverse mechanism from the under side of the table 8|at its righthand end .(Fig. 3). Similarly the cylinder IOI contains a'slidably mounted piston I05 which is connected by means of a piston rodI05 with a bracket I01 depending from the under side of the table 4| atits left-hand end.

A table reversing valve H0 is provided to control the passage of fluidunder pressure through a pipe III into a cylinder chamber II2 within thecylinder I M, or through apipe II3 into a cylinder chamber III formedwithin the table cylinder I00. The reversing valve H0 is a piston typereversing valve comprising a valve stem II5 having formed integrallytherewith the valve pistons H6, H1, H8, II9,.I20, I2I. I22 and I23.

A fluid pressure system is provided for conveying fluid under pressureto the various mechanisms of the machine, comprising a reservoir I25(Figs. 1, 2 and 31') which is preferably formed within the box-like base40 of the grinding machine. Fluid is pumped from the reservoir I25 bymeans of a motor driven fluid pressure pump I25 which draws fluidthrough a pipe I21 and forces the fluid under pressure through a pipeI28 into the valve chamber located between the valve pistons I20 andI2I. Fluid under pressure is also simultaneously passed from the pipeI28, through the pipe I29 (Figs. 3, 9 and 12), into the valve chamberlocated between the valve pistons H8 and H9. In the position of thevalve stem II5 (Fig. 3), fluid under pressure also enters the valvechamber betweenthe'valve .pistons Ill and H8. An adjustable relief valveI30 is connected in the pipe line I28 and serves to return excess fluidunder pressure to the reservoir I25. Excess fluid under pressure withinthe pipe I28 serves to open the relief valve I30 and exhaust excessfluid under-pressure through a pipe I3I into the reservoir I25.

A second motor driven fluid pressure pump I35 is provided for pumpingfluid through a pipe I36 from the reservoir I25 and forcing fluid underpressure through a pipe I31 into a valve chamber located between thevalve pistons I2I and I22 and also to convey fluid under pressure fromthe pipe I31 through a pipe I38 into the valve chamber located betweenthe valve pistons II! and H8 (Fig. 3). The admission of fluid underpressure to the end chambers of the valve .I I0 serves to aid inshifting the reversing valve into its reverse position. The fluidpressure pump I35, in addition to conveying fluid under pressure to aidin the shifting of the table reversing valve III), also serves to supplyfluid under pressure to other fluid pressure operated mechanisms of themachine which will be hereinafter described. A relief valve I39connected with the pipe line I 31 serves to exhaust excess fluid underpressure through a pipe I 48 intothe' reservoir I28. 3 c

Reverse valve 'actaatiag. mechanism A reversing lever I44 (Figs 4, 8 and9)' is mounted on the front of the machine base; The

lever I44 is formed as abell crank lever. having outwardly. projectingarms I48 and I48 which serve as supports for r'otatablymoun'ted rollersI41 and 8.. The reversing lever I44 is fixedly 10 mountedlon the upperend of a rock shaft I48. The shaft I48 is arranged in a substantiallyvertical position and is supported in bearings I58 and III. The bearingsI88 and ISI arein turn supported ina rotatable sleeve I52 which is inturn rotatablysupported within an aperture I58 formed within a tablereversing apron I84 which is fixedly mounted on the front of the machinebase 48 (see Figs. 4, 8 and 9). v

The roller I41 is rotatably mounted on the upper end of a stud I88 whichis'fixedly mounted relative to the reversing lever arm' I48. The rollerI41 is arranged in the path of a cam face continued shifting movement ofthe lever. I88

serves to shift the reversing valve stem III end- A with .a gear segmentI83. The gear segment I88 is formed integral with the lower end of thestud I55 which is supported on the end of the arm I45. It will bereadily apparent from the foregoing disclosure that when the manuallyoperable table reversing lever I88 is shifted in a clockwise direction(Fig. 8) into dotted line position I88a. the gear segment I82, throughthe gear segment I88,shifts the reversing lever I44 I58 formed on atable dog I81 which is adjustably supportedby meansof a T-slot I58formed in the front edge of the work table 4I.

The roller I48 is mounted on the upper end 'of a vertically, movablestud I88 which is slidably supported within an aperture adjacent to theend of the. arm I48 of the reversing lever I44. The roller I48 is shownin its uppermost position, in which position it lies within'the path ofa cam face I88 formed on a'dog 'I8I whi ch stops the table movementtoward the left (Fig. 1) after a grinding operation has been completed,to facilitate a. loading operation; When the grindingc'ycle is started,the roller I48 is moved downwardly into position I481: (as shown indotted lines in Figs. 4, 6 and 11), in which position the roller I48lies in the path of a cam face I82 formed on'the adjustably positionedreversing dog' I88- It should be noted that the cam faces I88 of the dogI81 and thecam' face I82 of the dog I88 are arranged to move indifferent horizontal planes so that there is no con-' flict between theactuating rollers l41 and I48, respectively.

A lever' l8l is adjustably fixed to the lower end of the rock shaft I48(Fig. 9). The other end of the lever I88 supports a stud I88 which'is ofthe grinding cycle.

stud I58 supporting the roller I48 is provided at operatively connectedin 'a manner to be here-' inafter described to actuate the reversingvalve II8. A rod I81 is supported by means of a'pair of brackets I88 andI88 which are in turn fixedly supported on opposite ends of the valvestem IIS. valve stem III (Figs. 8 and 9). A lost motion connection (Fig.10) is provided between the stud I68 and the rod I81. This connectionmay comprise a pair of collars I18 and "I which are fixedly mounted onthe shaft I81 (Fig. 18). A housing I12 surrounds the-rod I81 andcontains a compression spring I18. The compression spring I18 is locatedbetween a pair of washers I14 and I18, respectively, which are normallyThe rod I81 is arranged parallel to the held in the position illustratedin Fig. 10 by means of pins passing through the rod lifl.

When the lever I88 is shifted'to start the reversing movement of thevalve 8, the shoe I88 first moves the housing I12 longitudinally to takeup 70 lost motion between the collars I18 and "I, 78

in a counterclockwise direction, which movement is transmitted throughthe shaft I48 and the lever I manually to shift the reversing valve II8into its reverse position. By manually shifting the lever I88between'the full line position (Fig. 8) and the broken line position"la, the table 4I may be manually controlled as desired.

A suitable mechanism is provided for automatically shifting the rollerI48 downwardly into position I48a'(Figs. 4 and 11) at the start Thevertically slidable its lower .end with an L-shaped end I88 (Fig. 4)

which mates with a correspondingly shaped slot formed inthe uppersurface of a vertically slidable' member I88. A pull type solenoid I81mounted within'the apron I54 is connected by means of a rod I88 with themember I88. The rod I88 is adjustable to facilitate setting up themechanism as desired. The upper end of the rod v I88 is'provided with ahead I88 which fits within a central aperture I88 formed in the lowerend of the member.l88. A spring Isl surrounds'the' rod I88 and isinterposed between the head I88 and a cover plate I 82 which enclosesthe lower end of the aperture I88. .The rod I88 is normally held in anupward position by means of a spring I88'whichis interposed between anadjustable member I84 carried by the rod I88 and a stud I88 (Figs. 3 and4) which is fixedly mounted to the apron I84 which supports the member I88. It will be readily'apparent from the foregoing disclosure, that thespring I88 normally maintains the roller I48 in the full line position(Fig. 4). when the solenoid I81 is energized, it causes a downward,movement of the rod I88 which transmits a corresponding movementthrough.

the member I88 to shift'the roller I 48 downwardly into position I 48a(as shown in dotted lines in Fig. 4).

A-stud I88 is threaded into the member I88 and passes through -asubstantially L-shaped-1 slot 288 (Figs. 1, 4 and 11) formed in theapron I54. 288 limits the vertical movement of the member I88 as thestud I88 moves between full line position I88 and dotted line positionI88a (Fig. 11).

The spring I8I is provided to facilitatea manual lifting of the rollerI48 at any time during the grinding cycle. It will be readily apparentthat the operator may manually grasp the knob at the end of the stud I88and lift it from the dotted line position I880 into the full line posi-The vertical portion of the L-shaped slot tion I98 (Fig. 11), whichmovement compresses the spring I9| during. the vertical movement of themember I85 to raise the roller I48 from position |48a into full lineposition I48. This movement may be accomplished even though the solenoidI81 may be energized and a grinding cycle in process, thus facilitatingthe raising of the roller [48 into the position illustrated in Fig. 4 sothat it will be out of the path of the cam I52 on the dog I03 as thetable 4| travels toward the left to allow the table, to traverse beyondits normal reciprocatory stroke into a loading position. The L-slotconnection between the stud I59 and the vertically movable member I86serves to facilitate a transverse movement of the stud I59 relative tothe member I06 during a shifting movement of the reverse lever I44. Ifdesired, the roller I48 may be locked in position I481: by depressingthe stud I98 so that the stud I90 follows down the vertical portion ofthe L-shaped slot 200, and then moving the stud I98 toward the right(Fig. 8) within the horizontal portion of the L-shaped slot 200 to latchthe member I85 in a downward position. While the stud I90 is latched ina downward position, the table 4| will reciprocate through a stroke ascontrolled by the table dogs I51 and I63. I

Start and stop valve I In order to readily control the starting andstopping of the grinding cycle. a start and stop valve 205 (Figs. 3, 8and 9) is provided. This valve 205 is a piston type valve comprising avalve stem 205 having formed integrally there-.

201 and 208 into a position to start the grinding cycle.

A plurality of ports 220 arranged in a staggered relationship are formedin the sleeve of the stop and start valve 205 and serve as a speedcontrolling device for the table 4I- whereby the exhausting fluid fromthe table cylinders I00 or IM may readily be controlled to regulate thespeed of movement of the table 4|. In order to facilitate adiustment of.the valve 205 to regulate the speed, a stop mechanism is providedcomprising a stop lug or pin 22| (Figs. 8 and 11) which is fixedlyconnected to a flange or collar 222 carried by the valve stem 205. Thestop pin m is arranged so that it moves in the path of a rotatablyadJustable stop cam 223 (Figs. 8 and 11). The cam 225 is fixedly mountedon the inner end of a rotatable shaft 224 which is rotatably supportedin a bearing 225 formed with- .in the apron I54 (Fig. 11). A combinedactuating knob and dial 226 is slidably keyed to the front end of theshaft 224 which projects from to the same identical position onsuccessive fluid within these chambers may readily exhaust into thereservoir. A pipe 2|I is connected at one end to the chamber locatedbetween the valve pistons 201 and 208 of the stop and start valve 205and connects withthe pipe II3 (Fig. 3). A pipe 2|2 is connected betweenthe stop and start valve 205 at one end and at the other end connectswith the valve chamber located between the valve pistons IIS and I20of'the reversing valve IIO, so that in the position (Fig.-

grinding cycles.

At the end of the grinding cycle, when the solenoid is deenergized theroller I40 moves up to-pass over the cam I52 of'the dog |63 and thetable 4| movestoward the left (Fig. 1). The cam I 0! the dog 'IOIstrikes the roller I48 and shifts the reversing lever I45 and also thereversing valve 0 so that the table is ready to. move toward the right.when this occurs a depending plate 245 adjustably mounted on the dog |6|has an integral cam 240 (Figs. 6, 9 and ,12) which strikes a springlocated finger 241 pivotally mounted in a slot in the stop and startlever III. The finger 241 slides up the inclined left-hand face of thecam 240, rocking the lever M5 and stopping the table 4| by shifting thestop and start valve 205. The momentum ofthe table 4| will shift thelever 2l5 so that the fin.

' ger 241 will clear the-cam 240 (Fig. 8).

3) -a manual traverse of the table 4| is facilitated by a by-passing offluid between the cylinders I00 and IN.

The valve stem 200 of the stop and start valve 205 is preferablymanually controlled by means of a manually operable control lever 2I5(Figs. 8 and 9) mounted on the front of the machine base. The lever 2|5is fixedly mounted on the upper end of the rotatable sleeve I52. An armtit is also fixedly mounted adjacent to the lower end of the sleeve I52so that the lever M5, the sleeve it? and the arm 2E0 function as a bellcrank lever. The arm tit is connected by a stud 2i? with one end of alink 2I8. The other end of the link 2H3 is connected by means of a stud2|9 with the valve stem 206. It will be readily apparent from theforegoing disclosure that when the lever 255 is moved in a clocdirection (Fig. 8) from the full line position to the dotted lineposition Zita, the parts will be rocked to cause a downward movement ofthe when starting another grinding cycle, the

lever 2|.5 is manually moved clockwise into position 2|5a so that thefinger 241 will slide down the right-hand inclined face of the integralcam 24$ into the dot and dash position (Fig. 8). The table 4|reciprocates to the right (Fig. 4). The dog ISI also moves to the rightandthe cam 245 on the plate :45 supported by the dog IBI rides over thefinger 241, swinging it into the recess or groove (Fig. 8) on the lever2|5. After clearing the cam 245, the tension of the spring 240 returnsthe finger 241 to its initial position ready 'i'or stopping the table atthe end 0! thegrinding cycle.

A c see (Figs. 3 and 9) formed integral the limit switch 280 serves toset in motion a fully automatic tantanecus reset electrical counter 238such a, ior example, that known valve stem its (Fig. 8) to shift thevalve pistons as the crofiex instantaneous reset counter and-need onlybe reset when the operator deslres to change the cycle of operation ofthe machine.

Interlock-hand and hydraulic table traverse It is desirable to providean interlocking mech .anism between the manually operable table traversemechanism and the hydraulically operated table reciprocating mechanismso that the hy-- draulic movement of the table 4i cannot be 7 startedunless the hand traverse mechanism is in an inoperative position. Arockarm 285 (Figs. 7 and 8) is pivotally supported on a stud 286. Theupper end of the rock arm .285 is connected by means of a stud 231 toone end of a link 288 (Figs. 7 and 8). The other end of the link 288 isconnected by a stud .288 carried by the link 2. An arcuate slot 248'(Fig. 8) is cut through the-housing surrounding the cylindrical bore 81,and into the slidably mounted sleeve 85 which supports the hand traversemechanism formovement into and out of an operative position. When thehand traverse mechanism is in an inoperative position, that is when thegear 8| is in the full lin position (Fig. 8) out of mesh with the rackbar 88, the arcuate slot 248 in the sleeve 85- is aligned with the Inorder to eliminate backlash between the screw 258 and the nut 255, asecond nut 256 is provided which also meshes with or engages the feedscrew 258. The nuts 255 and 256 are held in alignment with .each otherby means of a pair of pinsor studs 251 and 258 (Figs. '27 and 28) whichare arranged on diametrically opposite sides of the feed screw 258. Thepins or studs 251 and 258 tightly fit holes within the nut 255 andslidably engage holes formed in the nut 256 so that the nut 256 is heldin alignment with the nut 255 but is free to move in an endwise or axialdirection. -In order to take up the backlash between the screw 258 andthe nut 255, the nuts 255 and 256 are urged in opposite directions sothat the thrust thereof is always in the same direction relative to thescrew 258. To

accomplish this result, a wedge block 259 is interposed between the nuts255 and 256. The wedge block 258 straddles the screw 258, as will bereadily apparent from the illustration in Fig. 28. A spring 268, thecompression of which is adjustable by means of a screw, serves to urgethe wedge block 258 toward the right (Fig. 27) to take up the backlashbetween the nut 255 and the screw 258.

It is desirable to provide suitable safety devices to prevent the nuts:55 and m from moving portion of the slot. 248 through the housingsurrounding the sleeve 85. In this position of the handtraversemechanism, the manually operable stop and start lever 2i5 may bereadily opereatd to shift the start and stop valve stem 286 to start agrinding cycle.

During this shifting movement of the stop and start valve, the link 288(Fig. 8) moves toward the right, which movement swings the rock arm 285in a clockwise direction so that the enlarged arcuate lower end 2 of therock arm 285 slides within the arcuate slot v248. If the hand traversemechanism isin an operative position, that is, with the gear 8| in meshwith the .rack bar 88, the start and stop lever 215 canendwise intoengagement with'the bearing supports. This is preferably accomplished bymeans of mountingastud' 26l in the upper surface of the 'nut 255." ..Acollar 262 is adjustably clamped on a reduced, upper end portion ofthescrew 258. The collar 262 carries a stud 268 which is arrangedin'j'the path of the stud 26i. If the slide 48 and the nut 255 areraised above the upper endbfthe'screw threads on the feed screw 258,thestud .3268 will rotate into engagement with the'stud26l and thusprevent further rotathe lower end 2 will engage the periphery of' I thesleeve 85 which serves as a stop to'prevent shifting the stop' and startvalve 285 to start a grinding cycle. It will be readily apparent fromthe foregoing disclosure that an interlock is provided whereby themanually operable cycle stop and start valve .285 is renderedinoperative when the hand traversemechanism is in an operative position.The hand traverse mechanism is similarly rendered inoperativewhen thestop and start valve is in an operative position.

Vertical feed v A feeding mechanism is provided for moving the slide 48vertically to adjust the position of the grinding wheel 65 relative tothe work table 4| and the work piece to be ground. This mech. anism maycomprise a rotatable feed screw 258 (Fig. 27) which is iournalled at itsupper and lower ends in anti-friction bearings 25i, 252,

tion of thefeed screw258. Similarly, the"low'er nut 256 is provided witha stud mi .Af colla'r m is adjustably clamped on the lower reducede'ndportion of the feed screw 258. The'collar 255 carries a stud 266 whichis arrangeiin the path of the stud 254 so that in case the slide 48 islowered so that the nut 256 approaches the end of the threads on thefeed screw 2.58, the stud 266 will rotate into engagement with the fixedstud .264 and thus prevent furtherrotation of the feed screw 258.

A spiral gear 218 (Fig.2?) 'is keyed on the lower end of the feed screw258. The spiral gear 218 meshes with a spiral gear 2 which isformedintegral with a shaft 268 which is connected by means of a sleeve 268 toone end of a rotatable shaft 212 (Fig. 31). The shaft 268 is rotatablysupported in bearings 86l .aqi 882 (Fig. 31) in a housing 888 which isfixedly supported on the column 46. The shaft 212 (Fig. 12) extendshorizontally within the base 48 and is rotatably supported in bearings218 and 214 in the apron 261. A clutch plate 215 is fixedly mounted onthe outer end of the shaft 212. The clutch-plate 215 is provided withclutch teeth which are arranged to be engaged by clutch teeth 218 formedwithin a cup-shaped aperture within on the apron 261. A manuallyoperable feed 1

